Stephenson, who left the firm in March 2006 (20 Mar 2006), died in September after being struck by a train near Taplow station.
Buckinghamshire coroner Richard Hulett, sitting with a jury at Amersham Coroner's Court yesterday, recorded a verdict of suicide.
Stephenson joined Freshfields in 1999 as finance director and became managing director in 2004. At one point he was seen as a potential contender for the chief executive role. When he left the firm, his duties were taken on by chief executive Ted Burke, who had just been appointed to the role.
A spokesperson for the firm said: "Kirk Stephenson was a highly enjoyable and stimulating colleague who made a valuable difference to the firm; he will be sadly missed by many of us and our thoughts and sympathies are with his family and close friends."
At the time of his death Stephenson was chief operating officer and a partner at private equity house Olivant, which he helped set up after leaving Freshfields.
Prior to joining Freshfields Stephenson worked as group finance director of Coats Viyella and Amersham International.